Atomizing nozzle assembly

ABSTRACT

Liquid (e.g., paint) is sprayed with a nozzle having an axial flow passage and coaxial radial holes into the passage spaced 180* apart intermediate the nozzle inlet and outlet.

United States Patent Nathaniel Hughes Beverly Hills, Cnlll.

Sept. 4, 1969 Nov. 9, 1971 Energy Sciences, Incorporated El Segundo, Cnlll.

Inventor Appl. N 0. Filed Patented Assignee ATOMIZING NOZZLE ASSEMBLY 11 Claims, 2 Drawing Figs.

U.S. Cl 239/4l9.3, 239/102, 239/428. 239/596, 239/600 lnt.Cl. F23d "/16 Field of Search [56] Relerences Cited UNITED STATES PATENTS 2,219,696 10/1940 Mueller et al 239/419 2,737,419 3/1956 Marcuse 239/428 X 2,774,583 l2/1956 Haftke 239/427 X 3,3 30,484 7/1967 Johnson et al. 239/428 X 3,477,647 11/1969 Grundman et a1. 239/600 X 3,531,048 9/1970 Hughes 239/102 X 3,53 L050 9/1970 Abraham el al. 239/4273 Primary Examiner- Lloyd L. King Assistant Examiner-Thomas C. Culp, J r. Anorneywm. W. Rymer ABSTRACT: Liquid (e.g., paint) is sprayed with a nozzle having an axial flow passage and coaxial radial holes into the passage spaced 180 apart intermediate the nozzle inlet and outlet.

ATOMIZING NOZZLE ASSEMBLY This invention relates to spraying liquid, especially paint.

Objects of the invention are to provide an improved sprayer in which even very heavy liquid can be finely atomized and yet which can be operated at low liquid and air pressures and with low air consumption, and is simple, reliable, selfcleaning, and inexpensive to make and use. Other objects include provision of a wide, fan-shaped spray of uniform qualities,-so that, e.g.,

, paint can be applied to even a smooth, nonporous surface in a thin, smooth, fast drying, tightly adhered coat, all without requiring separate air outlets for shaping the spray; reduction of forward momentum and overspray characteristics of the paint, yet wit increase in paint flow capability; provision for control of the fan dimensions and of solvent removal by adjustment of the air pressure; and provision of a nozzle that is insensitive to liquid viscosity or to its distance from the work surface, and in which there are no critical orifices to clog.

The invention in one aspect features spraying paint by providing an atomizing' nozzle having a body with inlet and outlet ends and an axial flow passage therebetween, and as least a pair of coaxial radial holes into the passage spaced 180 apart intermediate the inlet and outlet ends; and supplying compressed air and paint to the nozzle at the inlet end and at the radial holes to produce a spray of atomized paint at the outlet end. In preferred embodiments air and paint are introduced through a single pair of radial 'holes to produce a fanshaped spray the long dimension of which is perpendicular to the common axis of those radial holes; air and paint are also introduced into the axial passage through a pair of openings arranged at the inlet end symmetrically at opposite sides of the nozzle axis and respectively angularly aligned with the two radial holes, each opening being shaped as a segment of a circle and having an area larger than that of a radial hole; air and paint are also introduced through an axial hole into the axial passage, and axial hole having an area less that that of either segment-shaped opening and of either radial hole; all air and paint is supplied through a reflector located upstream of the nozzle and having an axial opening and two additional openings arranged symmetrically at opposite sides of the axial opening, the three openings having their centers in a single plane perpendicular to the common axis of the radial holes, there also being small openings in the reflector closely adjacent the axial opening to partially relieve the hydraulic pressure drop thereacross; and the nozzle has a single outlet through a countersink to the axial passage.

in another aspect the invention features producing a fanshaped spray of atomized liquid by introducing a compressible fluid into a nozzle with an axial flow passage through a pair of radial holes downstream of the nozzle inlet, the holes having a common axis perpendicular to the long dimension of the fan.

Other objects, features, and advantages of the invention will be apparent from the following description of a preferred embodiment thereof, taken together with the drawings thereof, in which:

FIG. 1 is a view of a conventional paint sprayer modified to embody the invention, with the aircap partly broken away, some of the elements inside the aircap being shown in section; and

FIG. 2 is an exploded perspective perspective view of some of the elements of FIG. 1. Conventional paint sprayer head 10, with needle valve paint outlet 12 surrounded by air outlets 14, is mounted inside aircap 16, which is adapted to be secured to a conventional compressed air-operated spray gun (not shown) by threaded retainer ring 18. Cap 16 has an indicating groove 17 (FIG. 2).

Annular flange 20 of nozzle 22 is press fitted in the downstream end of axial bore 24 of cap 16, against flange 26 surrounding cap outlet 28 (outlet diameter 0.370

Disc-shaped reflector 30 (outside diameter 0.496 is press fitted in counterbore 32 of cap 16, between nozzle 22 and head 10. Reflector 30 has a central hole 33 (diameter 0.1 11 midway between two holes 34 (each 0.144 in diameter) having axes spaced 0.290 and coplanar with the axis of hole 32. Central hole 33 is concentric with an imaginary circle (diameter 0.136) containing the centers of four equally spaced holes 36 (diameter 0.135) arranged symmetrically about the line of centers of holes 33 and 34.

Nozzle 22 has a cylindrical wall 40 (outside diameter 0.346 inside diameter 0.260), open at its outlet end across 45 countersink 42, which is surrounded by flange 20. Axial inlet 44 (diameter 0.025) is provided in upstream end wall 46 which is relieved to provide two openings 48 into the nozzle, each opening 48 having the shape of a segment of a circle. 'The centers of openings 48 are respectively spaced angularly from the centers of holes 34. Two opposing coaxial radial holes 50 1 (each of diameter 0.073) through wall 40 are apart and tangent 'to countersink 42. The centers of inlet 44, openings 48, and holes 50 all lie in a single plane which is horizontal whenthe sprayer is oriented with groove 17 facing up (FIG. 2).

Additional nozzle dimensions are:

Length between downstream face of wall 46 and upstream end of countersink 42 0.148 Overall length of nozzle 0.209 Depth of countersink 42 0.029 Width of wall 46 between openings 48 0.190 Diameter of bore 24 upstream of flange 20 0.442 In operation, paint, and air at greater than atmospheric pressure are supplied to head 10 (held so that groove 17 faces up) in conventional manner and respectively enter cap 16 through outlets l2 and 14. The paint passes through hole 33 and most of the air passes through holes 34. Holes 36 relieve by about 20 percent the hydraulic pressure drop across hole 33, thus reducing the required paint pressure. Mixing takes place in bore 24, with paint and air in varying proportion passing into the nozzle through inlet 44, openings 48, and holes 50. Nozzle 22 atomizes the paint, which emerges from outlet 28 in a vertical, fan-shaped spray of very small droplets, due to the arrangement of holes 50 in a single opposing pair (although the spray would still be fan shaped if there were e. g., a pair of additional radial holes respectively spaced 90 from and smaller than holes 50.) Reflector 30 minimizes back spraying of paint against head 10, improves atomization, and, by the arrangement of holes 34 spaced 90 respectively from holes 50 and openings 48, increases the width of the fan.

in a typical operation, paint flow is 23 oz./minute, and airflow is 15 c.f.m. at 60 p.s.i.g. Air consumption decreases as paint flow is increased.

The subject matter disclosed herein relating to the aircap and provisions therein for mounting the nozzle and the reflector was the joint invention of Nathaniel Hughes and Edson B. Gould Ill.

Other embodiments will occur to those skilled in the art and are within the following claims.

What is claimed is:

l. Paint-spraying apparatus comprising:

an atomizing nozzle mounted downstream of a source of paint and compress air, said nozzle having a body with inlet and outlet ends in an axial flow passage extending therebetween, and

at least one pair of coaxial radial holes into said passage spaced 180 apart intermediate said ends, and

a perforated reflector mounted between said source and said nozzle, said paint and air being supplied to said nozzle through said reflector.

2. The apparatus of claim 1 wherein said reflector has an axial opening and additional openings arranged symmetrically at opposite sides of said axial opening, said paint being supplied through said axial opening.

3. The apparatus of claim 1 wherein said reflector is arranged so that at least the major volume of said air is supplied through zones out of angular alignment with said radial holes of said one pair.

4. The apparatus of claim 2, wherein said openings in said reflector have centers in a single plane perpendicular to the common axis of said radial holes.

5. The apparatus of claim 2 wherein openings are provided in said reflector adjacent said axial opening to partially relieve the hydraulic pressure drop thereacross.

6. Paint-spraying apparatus comprising:

an atomizing nozzle mounted downstream of a source of 5 paint and compressed air, said nozzle having a body with inlet and outlet ends and an axial flow passage therebetween, and

at least one pair of coaxial radial holes into said passage spaced 180 apart intermediate said ends, said holes of said one pair each being larger than any other said radial holes, whereby a fan-shaped spray is produced at said outlet end, the long dimension of said fan being perpendicular to the common axis of said radial holes of said one pair.

7. The apparatus of claim 6 wherein there is a single coaxial pair only of said radial holes.

8. The apparatus of claim 6 wherein a pair of openings are provided into said axial passage at said inlet end arranged symmetrically at opposite sides of the nozzle axis and respectively angularly aligned with said one pair of radial holes.

9. The apparatus of claim 8 wherein each said inlet end opening has the shape of a segment of a circle.

10. The apparatus of claim 8 wherein said inlet end openings each have an area larger than that of a said radial hole of said one pair.

11. The apparatus of claim 8 further comprising an axial inlet hole to said axial passage of area less than that of either said inlet end opening and either said radial hole of said one pair. 

1. Paint-spraying apparatus comprising: an atomizing nozzle mounted downstream of a source of paint and compressed air, said nozzle having a body with inlet and outlet ends and an axial flow passage extending therebetween, and at least one pair of coaxial radial holes into said passage spaced 180* apart intermediate said ends, and a perforated reflector mounted between said source and said nozzle, said paint and air being supplied to said nozzle through said reflector.
 2. The apparatus of claim 1 wherein said reflector has an axial opening and additional openings arranged symmetrically at opposite sides of said axial opening, said paint being supplied through said axial opening.
 3. The apparatus of claim 1 wherein said reflector is arranged so that at least the major volume of said air is supplied through zones out of angular alignment with said radial holes of said one pair.
 4. The apparatus of claim 2, wherein said openings in said reflector have centers in a single plane perpendicular to the common axis of said radial holes.
 5. The apparatus of claim 2 wherein openings are provided in said reflector adjacent said axial opening to partially relieve the hydraulic pressure drop thereacross.
 6. Paint-spraying apparatus comprising: an atomizing nozzle mounted downstream of a source of paint and compressed air, said nozzle having a body with inlet and outlet ends and an axial flow passage therebetween, and at least one pair of coaxial radial holes into said passage spaced 180* apart intermediate said ends, said holes of said one pair each being larger than any other said radial holes, whereby a fan-shaped spray is produced at said outlet end, the long dimension of said fan being perpendicular to the common axis of said radial holes of said one pair.
 7. The apparatus of claim 6 wherein there is a single coaxial pair only of said radial holes.
 8. The apparatus of claim 6 wherein a pair of openings are provided into said axial passage at said inlet end arranged symmetrically at opposite sides of the nozzle axis and respectively angularly aligned with said one pair of radial holes.
 9. The apparatus of claim 8 wherein each said inlet end opening has the shape of a segment of a circle.
 10. The apparatus of claim 8 wherein said inlet end openings each have an area larger than that of a said radial hole of said one pair.
 11. The apparatus of claim 8 further comprising an axial inlet hole to said axial passage of area less than that of either said inlet end opening and either said radial hole of said one pair. 